Dispatch method and apparatus for combined heat and power system

ABSTRACT

The present disclosure provides a dispatch method and apparatus for controlling a combined heat and power CHP system. The CHP system includes CHP units, non-CHP thermal units, wind farms and heating boilers; the CHP units, the non-CHP thermal units and the wind farms form an electric power system EPS of the CHP system; the CHP units and the heating boilers form a central heating system CHS of the CHP system; and the EPS and the CHS are isolable. The method includes: establishing a combined heat and power dispatch CHPD model, an objective function being a minimizing function of a total generation cost of the CHP units, the non-CHP thermal units, the wind farms and the heating boilers; solving the CHPD model based on Benders decomposition to obtain dispatch parameters for the EPS and the CHS; and controlling the EPS and the CHS according to the corresponding dispatch parameters respectively.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and benefits of Chinese PatentApplication No. 201710097510.9, filed with the State IntellectualProperty Office of P. R. China on Feb. 22, 2017, the entire contents ofwhich are incorporated herein by reference.

FIELD

The present disclosure relates to the power system operation technologyfield, and more particularly, to a dispatch method and a dispatchapparatus for a combined heat and power system.

BACKGROUND

A combined heat and power (CHP for short) system may include electricpower systems (EPSs for short) and central heating systems (CHSs forshort). For example, the CHP system may include CHP units, non-CHPthermal units, wind farms and heating boilers. The CHP units areconfigured to generate electricity for the EPSs and useful heat for theCHSs at the same time. However, utilization of wind power in the CHPsystem has encountered a critical problem in winter. For example, thewind resources are abundant but the electricity load is insufficient.More seriously, a significant conflict exists between the CHSs and windpower utilization. CHSs are supplied by the CHP units, and thegeneration output of a CHP unit is determined solely by the heat loaddemand A typical daily residential heat load curve peak occurs atnighttime, which is exactly when the daily curve of wind power peaks.Due to heating supply priority, CHP units must generate a large amountof electricity overnight, and thus wind power generation must berestricted. This conflict between the central heating supply and windpower utilization exists in urban areas with CHSs all over the world.

SUMMARY

Embodiments of the present disclosure provide a dispatch method forcontrolling a combined heat and power (CHP for short) system. The CHPsystem includes CHP units, non-CHP thermal units, wind farms and heatingboilers; the CHP units, the non-CHP thermal units and the wind farmsform an electric power system (EPS for short) of the CHP system; the CHPunits and the heating boilers form a central heating system (CHS forshort) of the CHP system; and the EPS and the CHS are isolable. Themethod includes: establishing a combined heat and power dispatch (CHPDfor short) model of the CHP system, in which an objective function ofthe CHPD model is a minimizing function of a total generation cost ofthe CHP units, the non-CHP thermal units, the wind farms and the heatingboilers and constraints of the CHPD model are established based ongeneration cost of the CHP units, the non-CHP thermal units, the windfarms and the heating boilers; solving the CHPD model based on Bendersdecomposition to obtain dispatch parameters for the EPS and the CHS; andcontrolling the EPS and the CHS according to the corresponding dispatchparameters respectively.

Embodiments of the present disclosure provide a dispatch device forcontrolling a CHP system. The CHP system includes CHP units, non-CHPthermal units, wind farms and heating boilers; the CHP units, thenon-CHP thermal units and the wind farms form an EPS of the CHP system;the CHP units and the heating boilers form a CHS of the CHP system; andthe EPS and the CHS are isolable. The device includes a processor; and amemory for storing instructions executable by the processor, in whichthe processor is configured to perform the above dispatch method forcontrolling a CHP system.

Embodiments of the present disclosure provide a non-transitorycomputer-readable storage medium having stored therein instructionsthat, when executed by a processor of a computer, causes the computer toperform the above dispatch method for controlling a CHP system.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to explicitly illustrate embodiments of the present disclosure,a brief introduction for the accompanying drawings corresponding to theembodiments will be listed as follows. Apparently, the drawingsdescribed below are only corresponding to some embodiments of thepresent disclosure, and those skilled in the art may obtain otherdrawings according to these drawings without creative labor.

FIG. 1 is a schematic diagram of a combined heat and power (CHP) systemaccording to an exemplary embodiment.

FIG. 2 is a flow chart of a dispatch method for a CHP system accordingto an exemplary embodiment.

FIG. 3 is a flow chart of a method for solving a CHPD model according toanother exemplary embodiment.

DETAILED DESCRIPTION

In order to make objectives, technical solutions and advantages of thepresent disclosure clearer, in the following the present disclosure willbe described in detail with reference to drawings. Apparently, thedescribed embodiments are only some embodiments of the presentdisclosure and do not represent all the embodiments. Based on theembodiment described herein, all the other embodiments obtained by thoseskilled in the art without creative labor belong to the protection scopeof the present disclosure.

FIG. 1 is a schematic diagram of a combined heat and power (CHP forshort) system according to an exemplary embodiment. As illustrated inFIG. 1, the CHP system includes a non-CHP thermal unit1, a non-CHPthermal unit 2, a wind farm 3, a CHP unit 4, and a heating boiler 5. Thenon-CHP thermal unit1, the non-CHP thermal unit 2, the wind farm 3 andthe CHP unit 4 form an electric power system (EPS for short) of the CHPsystem. The CHP unit 4 and the heating boiler 5 form a central heatingsystem (CHS for short) of the CHP system. The EPS and the CHS areisolable. In addition, FIG. 1 also illustrates loads and first nodes inthe EPS, and second nodes and heat exchange stations in the CHS.

FIG. 2 is a flow chart of a dispatch method for a CHP system accordingto an exemplary embodiment. As illustrated in FIG. 2, the methodincludes followings.

At block 10, a combined heat and power dispatch (CHPD for short) modelof the CHP system is established. An objective function of the CHPDmodel is a minimizing function of a total generation cost of the CHPunits, the non-CHP thermal units, the wind farms and the heating boilersand constraints of the CHPD model are established based on generationcost of the CHP units, the non-CHP thermal units, the wind farms and theheating boilers.

At block 20, the CHPD model is solved based on Benders decomposition toobtain dispatch parameters for the EPS and the CHS.

At block 30, the EPS and the CHS are controlled respectively accordingto the corresponding dispatch parameters.

In the following, the dispatch method will be described in detail.

(1) The CHPD model of the CHP system is established. The CHPD modelincludes the objective function and the constraints. The CHPD model isdescribed in detail as follows.

(1-1) The objective function of the CHPD model

The objective function of the CHPD model aims to minimize a totalgeneration cost of the CHP units, the non-CHP thermal units, the windfarms and the heating boilers. The total generation cost is establishedby a formula of

$\sum\limits_{t \in T}\left( {{\sum\limits_{i \in I^{CHP}}C_{i,t}^{CHP}} + {\sum\limits_{i \in I^{TU}}C_{i,t}^{TU}} + {\sum\limits_{i \in I^{WD}}C_{i,t}^{WD}} + {\sum\limits_{i \in I^{HB}}C_{i,t}^{HB}}} \right)$

where, t represents a dispatch time period, T represents an index set ofdispatch time periods, I^(CHP) represents an index set of the CHP units,I^(TU) represents an index set of the non-CHP thermal units, I^(WD)represents an index set of the wind farms, I^(HB) represents an indexset of the heating boilers, C_(i,t) ^(CHP) represents a generation costfunction of CHP unit i during period t, C_(i,t) ^(TU) represents ageneration cost function of non-CHP thermal unit i during the period t,C_(i,t) ^(WD) represents a generation cost function of wind farm iduring the period t, and C_(i,t) ^(HB) represents a generation costfunction of heating boiler i during the period t.

The generation cost function of the CHP unit i during the period t isestablished by a formula of

C _(i,t) ^(CHP)(p _(i,t) ^(CHP) ,q _(i,t) ^(CHP))=C _(i) ^(CHP,0) +C_(i) ^(CHP,p1) ·p _(i,t) ^(CHP) +C _(i) ^(CHP,q1) ·q _(i,t) ^(CHP) +C_(i) ^(CHP,p2)·(p _(i,t) ^(CHP))² +C _(i) ^(CHP,q2)·(q _(i,t) ^(CHP))²+C _(i) ^(CHP,pq2) ·p _(i,t) ^(CHP) q _(i,t) ^(CHP) ,∀iϵI ^(CHP) ,∀tϵT

where, C_(i) ^(CHP,0), C_(i) ^(CHP,p1), C_(i) ^(CHP,q1), C_(i)^(CHP,p2), C_(i) ^(CHP,q2) and C_(i) ^(CHP,pq2) represent generationcost coefficients of the CHP unit i, p_(i,t) ^(CHP) represents a poweroutput of the CHP unit i during the period t, and q_(i,t) ^(CHP)represents a heat output of the CHP unit i during the period t. Thegeneration cost coefficients are characteristic parameters of the CHPunit.

The generation cost function of the non-CHP thermal unit i during theperiod t is established by a formula of

C _(i,t) ^(TU)(p _(i,t) ^(TU))=C _(i) ^(TU,0) +C _(i) ^(TU,p1) p _(i,t)^(TU) +C _(i) ^(TU,p2)·(p _(i,t) ^(TU))² ,∀iϵI ^(TU) ,∀tϵT

and C_(i) ^(TU,0), C_(i) ^(TU,p1) and C_(i) ^(TU,p2) representgeneration cost coefficients of the non-CHP thermal unit i, and p_(i,t)^(TU) represents a power output of the non-CHP thermal unit i during theperiod t. Similarly, the generation cost coefficients are characteristicparameters of the non-CHP thermal unit.

The generation cost function of the wind farm i during the period t isestablished by a formula of

C _(i,t) ^(WD)(p _(i,t) ^(WD))=C _(i) ^(WD,ply)( P _(i,t) ^(WD) −p_(i,t) ^(WD))² ,∀iϵI ^(WD) ,∀tϵT

where, C_(i) ^(WD,pty) represents a penalty coefficient, P_(i,t) ^(WD)represents an available power output of the wind farm i during theperiod t and p_(i,t) ^(WD) represents a power output of the wind farm iduring the period t. A value of the penalty coefficient is determinedaccording to consumption demands of wind power, which is adjusted by apower system dispatching center according to a dispatch feedback result.

The generation cost function of the heating boiler i during the period tis established by a formula of

C _(i,t) ^(HB)(q _(i,t) ^(HB))=C _(i) ^(HB) ·q _(i,t) ^(HB) ,∀iϵI ^(HB),∀tϵT

where, C_(i) ^(HB) represents a generation cost coefficient of theheating boiler i, which is a characteristic parameter of the heatingboiler i, and q_(i,t) ^(HB) represents a heat output of the wind farm iduring the period t.

(1-2) The constraints of the CHPD model

The constraints of the CHPD model include constraints of the EPS andconstraints of the CHS.

The constraints of the EPS include operation constraints of the CHPunits, ramping up and down constraints of the CHP units, operationconstraints of the non-CHP thermal units, ramping up and downconstraints of the non-CHP thermal units, spinning reserve constraintsof the non-CHP thermal units, operation constraints of the wind farms, apower balance constraint of the EPS, a line flow limit constraint of theEPS, and a spinning reserve constraint of the EPS.

The constraints of the CHS include: constraints between supply/returnwater temperature differences of nodes and heat outputs, heat outputconstraints of the heating boilers, supply water temperature constraintsat nodes with heat sources connected, constraints between supply/returnwater temperature differences of nodes and heat exchanges of heatexchange stations, return water temperature constraints of heat exchangestations, and operation constraints of heating networks of the CHS.

(1-2-1) The constraints of the EPS.

The operation constraints of the CHP units are denoted by a formula of

${P_{i,t}^{CHP} = {\sum\limits_{\gamma \in {NE}_{i}}{\alpha_{i,t}^{\gamma}P_{i}^{\gamma}}}},{q_{i,t}^{CHP} = {\sum\limits_{\gamma \in {NE}_{i}}{\alpha_{i,t}^{\gamma}Q_{i}^{\gamma}}}},{0 \leq \alpha_{i,t}^{\gamma} \leq 1},{{\sum\limits_{\gamma \in {NE}_{i}}\alpha_{i,t}^{\gamma}} = 1},{\forall{i \in I^{CHP}}},{\forall{t \in T}}$

where, NE_(i) represents an index set of extreme points of the CHP uniti, P_(i) ^(γ), Q_(i) ^(γ) represent respectively a power output atextreme point γ of the CHP unit i and a heat output at the extreme pointγ of the CHP unit i, and α_(i,t) ^(γ) represents a convex combinationcoefficient of the extreme point γ of the CHP unit i during the periodt. The extreme points refer to points formed by heat output limits andpower output limits of the CHP units.

The ramping up and down constraints of the CHP units are denoted by aformula of

−RD _(i) ^(CHP) ·ΔT≤p _(i,t+1) ^(CHP) −p _(i,t) ^(CHP) ≤RU _(i) ^(CHP)·ΔT,∀iϵI ^(CHP) ,∀tϵT

where, RU_(i) ^(CHP) represents an upward ramp rate of the CHP unit i,RD_(i) ^(CHP) represents a downward ramp rate of the CHP unit i,p_(i,t+1) ^(CHP) represents a power output of the CHP unit i duringperiod t+1, and ΔT represents a dispatch interval.

The operation constraints of the non-CHP thermal units are denoted by aformula of

P _(i) ^(TU) ≤p _(i,t) ^(TU)≤ P _(i) ^(TU) ,∀iϵI ^(TU) ,∀tϵT

where, P_(i) ^(TU) represents an upper output bound of the non-CHPthermal unit i, and P_(i) ^(TU) represents a lower output bound of thenon-CHP thermal unit i.

The ramping up and down constraints of the non-CHP thermal units aredenoted by a formula of

−RD _(i) ^(TU) ·ΔT≤p _(i,t+1) ^(TU) −p _(i,t) ^(TU) ≤RU _(i) ^(TU)Δ·T,∀iϵI ^(TU) ,∀tϵT

where, RU_(i) ^(TU) represents an upward ramp rate of the non-CHPthermal unit i, RD_(i) ^(TU) represents a downward ramp rate of thenon-CHP thermal unit i, and p_(i,t+1) ^(TU) represents a power output ofthe non-CHP thermal unit i during period t+1.

The spinning reserve constraints of the non-CHP thermal units aredenoted by a formula of

0≤ru _(i,t) ^(TU) ≤RU _(i) ^(TU) ,ru _(i,t) ^(TU)≤ P _(i) ^(TU) −p_(i,t) ^(TU) ,∀iϵI ^(TU) ,∀tϵT

0≤rd _(i,t) ^(TU) ≤RD _(i) ^(TU) ,rd _(i,t) ^(TU) ≤p _(i,t) ^(TU)− P_(i) ^(TU) ,∀iϵI ^(TU) ,∀tϵT

where, ru_(i,t) ^(TU) represents an upward spinning reserve contributionof the non-CHP thermal unit i during the period t, and rd_(i,t) ^(TU)represents a downward spinning reserve contribution of the non-CHPthermal unit i during the period t.

The operation constraints of the wind farms are denoted by a formula of

0≤p _(i,t) ^(WD) ≤P _(i) ^(WD) ,∀iϵI ^(WD) ,∀tϵT

where, p_(i,t) ^(WD) represents a power output of the wind farm i duringthe period t, and P_(i,t) ^(WD) represents an available power output ofthe wind farm i during the period t.

The power balance constraint of the EPS is denoted by a formula of

${{{\sum\limits_{i \in I^{CHP}}p_{i,t}^{CHP}} + {\sum\limits_{i \in I^{TU}}p_{i,t}^{TU}} + {\sum\limits_{i \in I^{WD}}p_{i,t}^{WD}}} = {\sum\limits_{m \in I^{LD}}D_{m,t}}},{\forall{t \in T}}$

where, I^(LD) represents an index set of loads in the EPS and D_(m,t)represents a power demand of load m in the EPS during the period t.

The line flow limit constraint of the EPS is denoted by a formula of

$\left| {\sum\limits_{l \in I^{EPS}}{{SF}_{j - 1} \cdot \left( {{\sum\limits_{i \in I_{{EPS},l}^{CHP}}p_{i,t}^{CHP}} + {\sum\limits_{i \in I_{{EPS},l}^{TU}}p_{i,t}^{TU}} + {\sum\limits_{i \in I_{{EPS},l}^{WD}}p_{i,t}^{WD}} - {\sum\limits_{m \in I_{{EPS},l}^{LD}}D_{m,t}}} \right)}} \middle| {\leq L_{j}} \right.,{\forall{j \in I^{LN}}},{\forall{t \in T}}$

where, I^(EPS) represents an index set of buses in the EPS, SF_(j-l)represents a shift factor for bus l on line j of the EPS, I_(EPS,l)^(CHP) represents an index set of CHP units connected to the bus l ofthe EPS, I_(EPS,l) ^(TU) represents an index set of non-CHP thermalunits connected to the bus l of the EPS, I_(EPS,l) ^(WD) represents anindex set of wind farms connected to the bus l of the EPS, I_(EPS,l)^(LD) represents an index set of loads connected to the bus l of theEPS, L_(i) represents a flow limit of the line j of the EPS, and I^(LN)represents an index set of lines in the EPS.

The spinning reserve constraint of the EPS is denoted by a formula of

${{\sum\limits_{i \in I^{TU}}{ru}_{i,t}^{TU}} \geq {SRU}_{t}},{{\sum\limits_{i \in I^{TU}}{rd}_{i,t}^{TU}} \geq {SRD}_{t}},{\forall{t \in T}}$

where, SRU_(t) represents an upward spinning reserve demand of the EPSduring the period t and SRD_(t) represents a downward spinning reservedemand of the EPS during the period t.

(1-2-2) The constraints of the CHS

(1-2-2-1) Heating constraints of heat sources of the CHP units and theheating boilers

The constraints between the supply/return water temperature differencesof the nodes and the heat outputs are denoted by a formula of

${{{\sum\limits_{i \in I_{{CHS},k}^{CHP}}q_{i,t}^{CHP}} + {\sum\limits_{i \in I_{{CHS},k}^{HB}}q_{i,t}^{HB}}} = {C \cdot M_{k}^{N} \cdot \left( {\tau_{k,t}^{S} - \tau_{k,t}^{R}} \right)}},{\forall{k \in I_{HS}^{CHS}}},{\forall{t \in T}}$

where, I_(CHS,k) ^(CHP) represents an index set of CHP units connectedto node k of the CHS, I_(CHS,k) ^(HB) represents an index set of heatingboilers connected to the node k of the CHS, C represents a specific heatcapacity of water, M_(k) ^(N) represents a total mass flow rate of waterat the node k of the CHS, τ_(k,t) ^(S) represents a water temperature ofthe node k in supply pipelines of the CHS during the period t, τ_(k,t)^(R) represents a water temperature of the node k in return pipelines ofthe CHS during the period t, and I_(HS) ^(CHS) represents an index setof nodes with heat sources connected in the CHS.

The heat output constraints of the heating boilers are denoted by aformula of

0≤q _(i,t) ^(HB) ≤Q _(i) ^(HB) ,∀iϵI ^(HB) ,∀tϵT

where, Q _(i) ^(HB) represents an upper heat output bound of the heatingboiler i.

The supply water temperature constraints at the nodes with heat sourcesconnected are denoted by a formula of

T _(k) ^(S) ≤τ_(k,t) ^(S)≤ T _(k) ^(S) ,∀kϵI _(HS) ^(CHS) ,∀tϵT

where, T_(k) ^(S) represents an upper bound of the water temperature atthe node k in the supply pipelines of the CHS and T_(k) ^(S) representsa lower bound of the water temperature at the node k in the supplypipelines of the CHS.

(1-2-2-2) Operation constraints of the heat exchange stations

The constraints between the supply/return water temperature differencesof the nodes and the heat exchanges of the heat exchange stations in theCHS are denoted by a formula of

${{\sum\limits_{n \in I_{{CHS},k}^{HES}}Q_{n,t}^{HES}} = {C \cdot M_{k}^{N} \cdot \left( {\tau_{k,t}^{S} - \tau_{k,t}^{R}} \right)}},{\forall{k \in I_{HES}^{CHS}}},{\forall{t \in T}}$

where, I_(CHS,k) ^(HES) represents an index set of heat exchangestations connected to node k of the CHS, Q_(n,t) ^(HES) represents aheat exchange of heat exchange station n during the period t, Crepresents a specific heat capacity of water, M_(k) ^(N) represents atotal mass flow rate of water at the node k of the CHS, and I_(HES)^(CHS) represents an index set of nodes with heat exchange stationsconnected in the CHS.

The return water temperature constraints of the heat exchange stationsare denoted by a formula of

T _(k) ^(R) ≤τ_(k,t) ^(R)≤ T _(k) ^(R) ,∀kϵI _(HES) ^(CHS) ,∀tϵT

where, T_(k) ^(R) represents an upper bound of the water temperature atthe node k in the return pipelines of the CHS and T_(k) ^(R) representsa lower bound of the water temperature at the node k in the returnpipelines of the CHS.

(1-2-2-3) Operation constraints of heating networks

The operation constraints of the heating networks of the CHS are denotedby a formula of

${{\sum\limits_{{k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},S}}\left( {M_{{k\; 2}\rightarrow{k\; 1}}^{B,S}{{HL}_{{k\; 2}\rightarrow{k\; 1}}^{S}\left( {\tau_{{{k\; 2}\rightarrow{k\; 1}},t}^{S,{temp}} - T_{t}^{AMB}} \right)}} \right)} = {\left( {\sum\limits_{{k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},S}}M_{{k\; 2}\rightarrow{k\; 1}}^{B,S}} \right)\left( {\tau_{{k\; 1},t}^{S} - T_{i}^{AMB}} \right)}},{\forall{{k\; 1} \in I^{CHS}}},{\forall{t \in T}}$${{\sum\limits_{{k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},R}}\left( {M_{{k\; 2}\rightarrow{k\; 1}}^{B,R}{{HL}_{{k\; 2}\rightarrow{k\; 1}}^{R}\left( {\tau_{{{k\; 2}\rightarrow{k\; 1}},t}^{R,{temp}} - T_{t}^{AMB}} \right)}} \right)} = {\left( {\sum\limits_{{k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},R}}M_{{k\; 2}\rightarrow{k\; 1}}^{B,R}} \right)\left( {\tau_{{k\; 1},t}^{R} - T_{i}^{AMB}} \right)}},{\forall{{k\; 1} \in I^{CHS}}},{\forall{t \in T}}$

where, M_(k2→k1) ^(B,S) represents a mass flow rate of water transferredfrom node k2 to node k1 in supply pipelines of the CHS, M_(k2→k1) ^(B,R)represents a mass flow rate of return water transferred from the node k2to the node k1 in return pipelines of the CHS, I_(CHS,k1) ^(CN,S)represents an index set of child nodes of the node k1 in supplypipelines of the CHS, I_(CHS,k1) ^(CN,R) represents an index set ofchild nodes of the node k1 in return pipelines of the CHS, T_(t) ^(AMB)represents an ambient temperature during the period t, HL_(k2→k1) ^(S)represents a heat transfer factor of water transferred from the node k2to the node k1 in supply pipelines of the CHS, HL_(k2→k1) ^(R)represents a heat transfer factor of water transferred from the node k2to the node k1 in return pipelines of the CHS.

HL_(k2→k1) ^(S) and HL_(k2→k1) ^(R) are calculated by a formula of

${{HL}_{{k\; 2}\rightarrow{k\; 1}}^{S} = {\exp \left( {- \frac{Y_{{k\; 2}\rightarrow{k\; 1}}^{S}L_{{k\; 2}\rightarrow{k\; 1}}^{S}}{{CM}_{{k\; 2}\rightarrow{k\; 1}}^{B,S}}} \right)}},{\forall{{k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},S}}},{\forall{{k\; 1} \in I^{CHS}}}$${{HL}_{{k\; 2}\rightarrow{k\; 1}}^{R} = {\exp \left( {- \frac{Y_{{k\; 2}\rightarrow{k\; 1}}^{R}L_{{k\; 2}\rightarrow{k\; 1}}^{R}}{{CM}_{{k\; 2}\rightarrow{k\; 1}}^{B,R}}} \right)}},{\forall{{k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},R}}},{\forall{{k\; 1} \in I^{CHS}}}$

where, Y_(k2→k1) ^(S) represents a heat transfer coefficient per unitlength of pipeline from the node k2 to the node k1 in the supplypipelines of the CHS, Y_(k2→k1) ^(R) represents a heat transfercoefficient per unit length of pipeline from the node k2 to the node k1in the return pipelines of the CHS, L_(k2→k1) ^(S) represents a lengthof the supply pipeline from the node k2 to the node k1, L_(k2→k1) ^(R)represents a length of the return pipeline from the node k2 to the nodek1.

τ_(k2→k1,t) ^(S,temp) and τ_(k2→k1,t) ^(R,temp) are intermediatevariables representing temperature of the node k1 and only considering atransfer delay of water from its child node k2, wherein τ_(k2→k1,t)^(S,temp) and τ_(k2→k1,t) ^(R,temp) are denoted by a formula of

τ_(k2→k1,t) ^(S,temp)=(└Φ_(k2→k1) ^(S)┘+1−Φ_(k2→k1) ^(S))τ_(k2,t−└Φ)_(k2→k1) _(S) _(┘) ^(S)+(Φ_(k2→k1) ^(S)−└Φ_(k2→k1) ^(S)┘)τ_(k2,t−└Φ)_(k2→k1) _(S) _(┘−1) ^(S) ,∀k2ϵI _(CHS,k1) ^(CN,S) ,∀k1ϵI ^(CHS) ,∀tϵT

τ_(k2→k1,t) ^(R,temp)=(└Φ_(k2→k1) ^(R)┘+1−Φ_(k2→k1) ^(R))τ_(k2,t−└Φ)_(k2→k1) _(R) _(┘) ^(R)+(Φ_(k2→k1) ^(R)−└Φ_(k2→k1) ^(R)┘)τ_(k2,t−└Φ)_(k2→k1) _(R) _(┘−1) ^(R) ,∀k2ϵI _(CHS,k1) ^(CN,R) ,∀k1ϵI ^(CHS) ,∀tϵT

where, Φ_(k2→k1) ^(S) represents transfer time periods of water from thenode k2 to the node k1 in supply pipelines of the CHS, Φ_(k2→k1) ^(R)represents transfer time periods of water from the node k2 to the nodek1 in return pipelines of the CHS, and └⋅┘ represents a rounding downoperator.

(2) The CHPD model established in (1) is transformed into a model in amatrix form.

In detail, the CHPD model is summarized as a following quadraticprogramming (QP) problem in the matrix form by a formula of:

${\min\limits_{x_{E},x_{H}}{C_{E}\left( x_{E} \right)}} + {C_{H}\left( x_{H} \right)}$s.t.  A_(E)x_(E) ≤ b_(E) A_(H)x_(H) ≤ b_(H) Dx_(E) + Ex_(H) ≤ f

where, x_(E) represents variables of the EPS, and the variables of theEPS comprises p_(i,t) ^(TU), ru_(i,t) ^(TU), rd_(i,t) ^(TU), p_(i,t)^(WD), p_(i,t) ^(CHP), q_(i,t) ^(CHP) and α_(i,t) ^(γ); and x_(H)represents variables of the CHS, and the variables of the CHS comprisesq_(i,t) ^(HB), τ_(k,t) ^(S) and τ_(k,t) ^(R).

C_(E) represents the objective function of the EPS and C_(H) representsthe objective function of the CHS. C_(E) refers to

$\sum\limits_{t \in T}\left( {{\sum\limits_{i \in I^{CHP}}C_{i,t}^{CHP}} + {\sum\limits_{i \in I^{TU}}C_{i,t}^{TU}} + {\sum\limits_{i \in I^{WD}}C_{i,t}^{WD}}} \right)$

and C_(H) refers to

$\sum\limits_{t \in T}{\left( {\sum\limits_{i \in I^{HB}}C_{i,t}^{HB}} \right).}$

A_(E)x_(E)≤b_(E) refers to the constraints of the EPS, which includesall constraints described in (1-2-1). Each row in A_(E) and b_(E) hasone-to-one correspondence with each constraint in the EPS. Each columnin A_(E) and b_(E) has one-to-one correspondence with each variable inthe EPS. Each element in A_(E) is a coefficient of a variablecorresponding to a column where the element is located in a constraintcorresponding to a row where the element is located. Elements in eachrow in b_(E) are inequality constant terms in the constraintcorresponding to the elements.

A_(H)x_(H)≤b_(H) refers to the constraints of the CHS except theconstraints between the supply/return water temperature differences ofthe nodes and the heat outputs, which includes the constraints describedin (1-2-2) except the constraints between the supply/return watertemperature differences of the nodes and the heat outputs. Each row inA_(H) and b_(H) has one-to-one correspondence with each constraint inthe CHS. Each column in A_(H) and b_(H) has one-to-one correspondencewith each variable in the CHS. Each element in A_(H) is a coefficient ofa variable corresponding to a column where the element is located in aconstraint corresponding to a row where the element is located. Elementsin each row in b_(H) are inequality constant terms in the constraintcorresponding to the elements.

Dx_(E)+Ex_(H)≤f refers to the constraints between the supply/returnwater temperature differences of the nodes and the heat outputsdescribed in (1-2-2), i.e. coupling constraints on the EPS and the CHS.Each row in D, E and f has one-to-one correspondence with eachconstraint in the coupling constraints on the EPS and the CHS. Each rowin D has one-to-one correspondence with each variable in the EPS. Eachrow in E has one-to-one correspondence with each variable in the CHS.Each element in D and E is a coefficient of a variable corresponding toa column where the element is located in a constraint corresponding to arow where the element is located. Elements in each row in f areinequality constant terms in the constraint corresponding to theelements.

(3) The CHPD model in the matrix form described in (2) is solved by theBenders decomposition.

FIG. 3 is a flow chart of a method for solving a CHPD model according toanother exemplary embodiment. As illustrated in FIG. 3, the methodincludes followings.

(3-1) Initializing: an iteration number m is initialized as 0, thenumber of optimal cuts p is initialized as 0 and the number of feasiblecuts q is initialized as 0. Then an EPS problem is solved to obtain asolution as x_(E) ^((m)) by a formula of

$\min\limits_{x_{E}}{C_{E}\left( x_{E} \right)}$s.t.  A_(E)x_(E) ≤ b_(E).

(3-2) A CHS problem is solved according to the solution x_(E) ^((m)) bya formula of

$\min\limits_{x_{E},x_{H}}{C_{H}\left( x_{H} \right)}$s.t.  A_(H)x_(H) ≤ bn_(H) Dx_(E) + Ex_(H) ≤ f x_(E) = x_(E)^((m)).

(3-2-1) If the CHS problem in (3-2) is feasible, p is increased by 1 andan optimal cut is generated as follows,

A _(p) ^(OC) x _(E) +b _(p) ^(OC),

where, A^(OC)=λ^(T), b^(OC)=C_(H←E)(x_(E) ^((m)))−λ^(T)x_(E) ^((m)), andλ represents a Lagrange multiplier of a constraint x_(E)=x_(E) ^((m)) in(3-2), and C_(H←E)(x_(E) ^((m))) represents an objective value of theCHS problem in (3-2).

(3-2-2) If the CHS problem in (3-2) is infeasible, q is increased by 1and an feasible cut is generated as follows,

A _(q) ^(FC) x _(E) ≤b _(q) ^(FC).

A_(q) ^(FC) and b_(q) ^(FC) are calculated according to following acts:

(3-2-2-1) denoting a feasibility problem of the CHS problem as a formulaof:

$\max\limits_{x_{H}}{0^{T}\mspace{14mu} x_{H}}$s.t.  A_(H)x_(H) ≤ b_(H) Dx_(E)^((m)) + Ex_(H) ≤ f;

(3-2-2-2) introducing a relaxation term ε to relax the feasibilityproblem of the CHS problem in (3-2-2-1) as a formula of:

$\max\limits_{x_{H},ɛ}{1^{T}\mspace{14mu} ɛ}$s.t.  A_(H)x_(H) ≤ b_(H) Dx_(E)^((m)) + Ex_(H) + 1^(T)  ɛ ≤ f ɛ ≤ 0;

(3-2-2-3) denoting a Lagrange multiplier of a constraintA_(H)x_(H)≤b_(H) in the relaxed feasibility problem of the CHS problem(3-2-2-2) as û and a Lagrange multiplier of a constraint Dx_(E)^((m))+Ex_(H)+1^(T)ε≤f in the relaxed feasibility problem (3-2-2-2) as{circumflex over (v)}; and calculating A_(q) ^(FC) and b_(q) ^(FC)according to a formula of:

A _(q) ^(FC) ={circumflex over (v)} ^(T) D,b _(q) ^(FC) =û ^(T) b _(H)+{circumflex over (v)} ^(T) f.

(3-3) The EPS problem is solved by a formula of

${\min\limits_{x_{E}}{C_{E}\left( x_{E} \right)}} + C_{H\leftarrow E}$s.t.  A_(E)x_(E) ≤ b_(E) C_(H ← E) ≥ 0C_(H ← E) ≥ A_(i)^(OC)x_(E) + b_(i)^(OC), i = 1, 2, …, pA_(i)^(FC)x_(E) ≤ b_(i)^(FC), i = 1, 2, …, q;

the iteration number m is increased by 1 and a solution is denoted asx_(E) ^((m)).

(3-4) A convergence is checked. If ∥x_(E) ^((m))−x_(E) ^((m-1))∥_(∞)<Δ,the iteration is terminated to obtain the dispatch parameters for theEPS and the CHS according to the solution, in which Δ is a convergencethreshold, for example, a value of A is 0.001, and then (3-5) isexecuted; and if ∥x_(E) ^((m))−x_(E) ^((m-1))∥^(∞)≥Δ, (3-2) is returned.

(3-5) The obtained solution is used as the dispatch parameters for theEPS and the CHS.

Embodiments of the present disclosure further provide a dispatchapparatus for controlling a CHP system. The device includes: aprocessor; and a memory for storing instructions executable by theprocessor. The processor is configured to perform the above method.

Embodiments of the present disclosure further provide a non-transitorycomputer readable storage medium. The non-transitory computer readablestorage medium according to embodiments of the present disclosure mayinclude instructions that, when executed by a processor of an apparatus,causes the apparatus to execute the above method.

The technical solutions provided by embodiments of the presentdisclosure have following advantageous effects.

In the technical solutions of the present disclosure, the CHPD model canbe established by combining the dispatch model of the EPS and thedispatch model of the CHS. An algorithm for solving the proposed CHPDmodel is provided based on Benders decomposition. In the providedalgorithm for solving the proposed CHPD model, the operator of the EPSand the operator of the CHS can optimize corresponding internal systemsindependently, and the global optimal solution of the CHPD model can beobtained based on the interactive iteration between the boundaryconditions of the EPS and CHS. The provided algorithm for solving theproposed CHPD model may have a good convergence rate and significantlyimprove an operation flexibility of the CHS.

Any process or method described in the flowing diagram or other meansmay be understood as a module, segment or portion including one or moreexecutable instruction codes of the procedures configured to achieve acertain logic function or process, and the preferred embodiments of thepresent disclosure include other performances, in which the performancemay be achieved in other orders instead of the order shown or discussed,such as in an almost simultaneous way or in an opposite order, whichshould be appreciated by those having ordinary skills in the art towhich embodiments of the present disclosure belong.

The logic and/or procedures indicated in the flowing diagram ordescribed in other means herein, such as a constant sequence table ofthe executable code for performing a logical function, may beimplemented in any computer readable storage medium so as to be adoptedby the code execution system, the device or the equipment (such a systembased on the computer, a system including a processor or other systemsfetching codes from the code execution system, the device and theequipment, and executing the codes) or to be combined with the codeexecution system, the device or the equipment to be used. With respectto the description of the present invention, “the computer readablestorage medium” may include any device including, storing,communicating, propagating or transmitting program so as to be used bythe code execution system, the device and the equipment or to becombined with the code execution system, the device or the equipment tobe used. The computer readable medium includes specific examples (anon-exhaustive list): the connecting portion (electronic device) havingone or more arrangements of wire, the portable computer disc cartridge(a magnetic device), the random access memory (RAM), the read onlymemory (ROM), the electrically programmable read only memory (EPROMM orthe flash memory), the optical fiber device and the compact disk readonly memory (CDROM). In addition, the computer readable storage mediumeven may be papers or other proper medium printed with program, as thepapers or the proper medium may be optically scanned, then edited,interpreted or treated in other ways if necessary to obtain the programelectronically which may be stored in the computer memory.

It should be understood that, each part of the present disclosure may beimplemented by the hardware, software, firmware or the combinationthereof. In the above embodiments of the present invention, theplurality of procedures or methods may be implemented by the software orhardware stored in the computer memory and executed by the proper codeexecution system. For example, if the plurality of procedures or methodsis to be implemented by the hardware, like in another embodiment of thepresent invention, any one of the following known technologies or thecombination thereof may be used, such as discrete logic circuits havinglogic gates for implementing various logic functions upon an applicationof one or more data signals, application specific integrated circuitshaving appropriate logic gates, programmable gate arrays (PGA), fieldprogrammable gate arrays (FPGA).

It can be understood by those having the ordinary skills in the relatedart that all or part of the steps in the method of the above embodimentscan be implemented by instructing related hardware via programs, theprogram may be stored in a computer readable storage medium, and theprogram includes one step or combinations of the steps of the methodwhen the program is executed.

In addition, each functional unit in the present disclosure may beintegrated in one progressing module, or each functional unit exists asan independent unit, or two or more functional units may be integratedin one module. The integrated module can be embodied in hardware, orsoftware. If the integrated module is embodied in software and sold orused as an independent product, it can be stored in the computerreadable storage medium.

The non-transitory computer-readable storage medium may be, but is notlimited to, read-only memories, magnetic disks, or optical disks.

Reference throughout this specification to “an embodiment,” “someembodiments,” “one embodiment”, “another example,” “an example,” “aspecific example,” or “some examples,” means that a particular feature,structure, material, or characteristic described in connection with theembodiment or example is included in at least one embodiment or exampleof the present disclosure. Thus, the appearances of the phrases such as“in some embodiments,” “in one embodiment”, “in an embodiment”, “inanother example,” “in an example,” “in a specific example,” or “in someexamples,” in various places throughout this specification are notnecessarily referring to the same embodiment or example of the presentdisclosure. Furthermore, the particular features, structures, materials,or characteristics may be combined in any suitable manner in one or moreembodiments or examples.

Although explanatory embodiments have been shown and described, it wouldbe appreciated by those skilled in the art that the above embodimentscannot be construed to limit the present disclosure, and changes,alternatives, and modifications can be made in the embodiments withoutdeparting from spirit, principles and scope of the present disclosure.

1. A dispatch method for a combined heat and power CHP system, wherein,the CHP system comprises CHP units, non-CHP thermal units, wind farmsand heating boilers; the CHP units, the non-CHP thermal units and thewind farms form an electric power system EPS of the CHP system; the CHPunits and the heating boilers form a central heating system CHS of theCHP system; the EPS and the CHS are isolable; and the method comprises:establishing a combined heat and power dispatch CHPD model of the CHPsystem, wherein an objective function of the CHPD model is a minimizingfunction of a total generation cost of the CHP units, the non-CHPthermal units, the wind farms and the heating boilers and constraints ofthe CHPD model are established based on generation cost of the CHPunits, the non-CHP thermal units, the wind farms and the heatingboilers; solving the CHPD model based on Benders decomposition to obtaindispatch parameters for the EPS and the CHS; and controlling the EPS andthe CHS according to the corresponding dispatch parameters respectively.2. The method according to claim 1, wherein the total generation cost isestablished by a formula of$\sum\limits_{t \in T}\left( {{\sum\limits_{i \in I^{CHP}}C_{i,t}^{CHP}} + {\sum\limits_{i \in I^{TU}}C_{i,t}^{TU}} + {\sum\limits_{i \in I^{WD}}C_{i,t}^{WD}} + {\sum\limits_{i \in I^{HB}}C_{i,t}^{HB}}} \right)$where, t represents a dispatch time period, T represents an index set ofdispatch time periods, I^(CHP) represents an index set of the CHP units,I^(TU) represents an index set of the non-CHP thermal units, I^(WD)represents an index set of the wind farms, I^(HB) represents an indexset of the heating boilers, C_(i,t) ^(CHP) represents a generation costfunction of CHP unit i during period t, C_(i,t) ^(TU) represents ageneration cost function of non-CHP thermal unit i during the period t,C_(i,t) ^(WD) represents a generation cost function of wind farm iduring the period t, and C_(i,t) ^(HB) represents a generation costfunction of heating boiler i during the period t.
 3. The methodaccording to claim 2, wherein the generation cost function of the CHPunit i during the period t is established by a formula ofC _(i,t) ^(CHP)(p _(i,t) ^(CHP) ,q _(i,t) ^(CHP))=C _(i) ^(CHP,0) +C_(i) ^(CHP,p1) ,p _(i,t) ^(CHP) +C _(i) ^(CHP,q1) ·q _(i,t) ^(CHP) +C_(i) ^(CHP,p2)·(p _(i,t) ^(CHP))² +C _(i) ^(CHP,q2)·(q _(i,t) ^(CHP))²+C _(i) ^(CHP,pq2) ·p _(i,t) ^(CHP) q _(i,t) ^(CHP) ,∀iϵI ^(CHP) ,∀tϵTwhere, C_(i) ^(CHP,0), C_(i) ^(CHP,p1), C_(i) ^(CHP,q1), C_(i)^(CHP,p2), C_(i) ^(CHP,q2) and C_(i) ^(CHP,pq2) represent generationcost coefficients of the CHP unit i, p_(i,t) ^(CHP) represents a poweroutput of the CHP unit i during the period t, and q_(i,t) ^(CHP)represents a heat output of the CHP unit i during the period t.
 4. Themethod according to claim 2, wherein the generation cost function of thenon-CHP thermal unit i during the period t is established by a formulaofC _(i,t) ^(TU)(p _(i,t) ^(TU))=C _(i) ^(TU,0) +C _(i) ^(TU,p1) p _(i,t)^(TU) +C _(i) ^(TU,p2)·(p _(i,t) ^(TU))² ,∀iϵI ^(TU) ,∀tϵT where, C_(i)^(TU,0), C_(i) ^(TU,p1) and C_(i) ^(TU,p2) represent generation costcoefficients of the non-CHP thermal unit i, and p_(i,t) ^(TU) representsa power output of the non-CHP thermal unit i during the period t.
 5. Themethod according to claim 2, wherein the generation cost function of thewind farm i during the period t is established by a formula ofC _(i,t) ^(WD)(p _(i,t) ^(WD))=C _(i) ^(WD,pty)( P _(i,t) ^(WD) −p_(i,t) ^(WD))² ,∀iϵI ^(WD) ,∀tϵT where, C_(i) ^(WD,pty) represents apenalty coefficient, P_(i,t) ^(WD) represents an available power outputof the wind farm i during the period t and p_(i,t) ^(WD) represents apower output of the wind farm i during the period t.
 6. The methodaccording to claim 2, wherein the generation cost function of theheating boiler i during the period t is established by a formula ofC _(i,t) ^(HB)(q _(i,t) ^(HB))=C _(i) ^(HB) ·q _(i,t) ^(HB) ,∀iϵI ^(HB),∀tϵT where, C_(i) ^(HB) represents a generation cost coefficient of theheating boiler i, and q_(i,t) ^(HB) represents a heat output of the windfarm i during the period t.
 7. The method according to claim 2, wherein,the constraints comprise constraints of the EPS and constraints of theCHS; the constraints of the EPS comprise: operation constraints of theCHP units, ramping up and down constraints of the CHP units, operationconstraints of the non-CHP thermal units, ramping up and downconstraints of the non-CHP thermal units, spinning reserve constraintsof the non-CHP thermal units, operation constraints of the wind farms, apower balance constraint of the EPS, a line flow limit constraint of theEPS, and a spinning reserve constraint of the EPS; and the constraintsof the CHS comprise: constraints between supply/return water temperaturedifferences of nodes and heat outputs, heat output constraints of theheating boilers, supply water temperature constraints at nodes with heatsources connected, constraints between supply/return water temperaturedifferences of nodes and heat exchanges of heat exchange stations,return water temperature constraints of heat exchange stations, andoperation constraints of heating networks of the CHS.
 8. The methodaccording to claim 7, wherein the operation constraints of the CHP unitsare denoted by a formula of${p_{i,t}^{CHP} = {\sum\limits_{\gamma \in {NE}_{i}}{\alpha_{i,t}^{\gamma}P_{i}^{\gamma}}}},{q_{i,t}^{CHP} = {\sum\limits_{\gamma \in {NE}_{i}}{\alpha_{i,t}^{\gamma}Q_{i}^{\gamma}}}},{0 \leq \alpha_{i,t}^{\gamma} \leq 1},{{\sum\limits_{\gamma \in {NE}_{i}}\alpha_{i,t}^{\gamma}} = 1},{{\text{∀}i} \in I^{CHP}},{{\text{∀}t} \in T}$where, p_(i,t) ^(CHP) represents a power output of the CHP unit i duringthe period t, q_(i,t) ^(CHP) represents a heat output of the CHP unit iduring the period t, NE_(i) represents an index set of extreme points ofthe CHP unit i, P_(i) ^(γ), Q_(i) ^(γ) represent respectively a poweroutput at extreme point γ of the CHP unit i and a heat output at theextreme point γ of the CHP unit i, and α_(i,t) ^(γ) represents a convexcombination coefficient of the extreme point γ of the CHP unit i duringthe period t; and the ramping up and down constraints of the CHP unitsare denoted by a formula of−RD _(i) ^(CHP) ·ΔT≤p _(i,t+1) ^(CHP) −p _(i,t) ^(CHP) ≤RU _(i) ^(CHP)·ΔT,∀iϵI ^(CHP) ,∀tϵT where, RU_(i) ^(CHP) represents an upward ramprate of the CHP unit i, RD_(i) ^(CHP) represents a downward ramp rate ofthe CHP unit i, p_(i,t+1) ^(CHP) represents a power output of the CHPunit i during period t+1, and ΔT represents a dispatch interval.
 9. Themethod according to claim 7, wherein the operation constraints of thenon-CHP thermal units are denoted by a formula ofP _(i) ^(TU) ≤p _(i,t) ^(TU)≤ P _(i) ^(TU) ,∀iϵI ^(TU) ,∀tϵT where,P_(i) ^(TU) represents an upper output bound of the non-CHP thermal uniti, P_(i) ^(TU) represents a lower output bound of the non-CHP thermalunit i and p_(i,t) ^(TU) represents a power output of the non-CHPthermal unit i during the period t; the ramping up and down constraintsof the non-CHP thermal units are denoted by a formula of−RD _(i) ^(TU) ·ΔT≤p _(i,t+1) ^(TU) −p _(i,t) ^(TU) ≤RU _(i) ^(TU)·ΔT,∀iϵI ^(TU) ,∀tϵT where, RU_(i) ^(TU) represents an upward ramp rateof the non-CHP thermal unit i, RD_(i) ^(TU) represents a downward ramprate of the non-CHP thermal unit, p_(i,t+1) ^(TU) represents a poweroutput of the non-CHP thermal unit i during period t+1, and ΔTrepresents a dispatch interval; and the spinning reserve constraints ofthe non-CHP thermal units are denoted by a formula of0≤ru _(i,t) ^(TU) ≤RU _(i) ^(TU) ,ru _(i,t) ^(TU)≤ P _(i) ^(TU) −p_(i,t) ^(TU) ,∀iϵI ^(TU) ,∀tϵT0≤rd _(i,t) ^(TU) ≤RD _(i) ^(TU) ,rd _(i,t) ^(TU) ≤p _(i,t) ^(TU)− P_(i) ^(TU) ,∀iϵI ^(TU) ,∀tϵT where, ru_(i,t) ^(TU) represents an upwardspinning reserve contribution of the non-CHP thermal unit i during theperiod t, and rd_(i,t) ^(TU) represents a downward spinning reservecontribution of the non-CHP thermal unit i during the period t.
 10. Themethod according to claim 7, wherein the operation constraints of thewind farms are denoted by a formula of0≤p _(i,t) ^(WD)≤ P _(i) ^(WD) ,∀iϵI ^(WD) ,∀tϵT where, p_(i,t) ^(WD)represents a power output of the wind farm i during the period t, andP_(i,t) ^(WD) represents an available power output of the wind farm iduring the period t.
 11. The method according to claim 7, wherein thepower balance constraint of the EPS is denoted by a formula of${{{\sum\limits_{i \in I^{CHP}}p_{i,t}^{CHP}} + {\sum\limits_{i \in I^{TU}}p_{i,t}^{TU}} + {\sum\limits_{i \in I^{WD}}p_{i,t}^{WD}}} = {\sum\limits_{m \in I^{LD}}D_{m,t}}},{{\text{∀}t} \in T}$where, p_(i,t) ^(CHP) represents a power output of the CHP unit i duringthe period t, p_(i,t) ^(TU) represents a power output of the non-CHPthermal unit i during the period t, p_(i,t) ^(WD) represents a poweroutput of the wind farm i during the period t, I^(LD) represents anindex set of loads in the EPS and D_(m,t) represents a power demand ofload m in the EPS during the period t; the line flow limit constraint ofthe EPS is denoted by a formula of${{{\sum\limits_{l \in I^{EPS}}{{SF}_{j - l} \cdot \left( {{\sum\limits_{i \in I_{{EPS},l}^{CHP}}p_{i,t}^{CHP}} + {\sum\limits_{i \in I_{{EPS},l}^{TU}}p_{i,t}^{TU}} + {\sum\limits_{i \in I_{{EPS},l}^{WD}}p_{i,t}^{WD}} - {\sum\limits_{m \in I_{{EPS},l}^{LD}}D_{m,t}}} \right)}}} \leq L_{j}},{{\text{∀}j} \in I^{LN}},{{\text{∀}t} \in T}$where, I^(EPS) represents an index set of buses in the EPS, SF_(j-l)represents a shift factor for bus l on line j of the EPS, I_(EPS,l)^(CHP) represents an index set of CHP units connected to the bus l ofthe EPS, I_(EPS,l) ^(TU) represents an index set of non-CHP thermalunits connected to the bus l of the EPS, I_(EPS,l) ^(WD) represents anindex set of wind farms connected to the bus l of the EPS, I_(EPS,l)^(LD) represents an index set of loads connected to the bus l of theEPS, L_(j) represents a flow limit of the line j of the EPS, and I^(LN)represents an index set of lines in the EPS; and the spinning reserveconstraint of the EPS is denoted by a formula of${{\sum\limits_{i \in I^{TU}}{ru}_{i,t}^{TU}} \geq {SRU}_{t}},{{\sum\limits_{i \in I^{TU}}{rd}_{i,t}^{TU}} \geq {SRD}_{t}},{{\text{∀}t} \in T}$where, ru_(i,t) ^(TU) represents an upward spinning reserve contributionof the non-CHP thermal unit i during the period t, rd_(i,t) ^(TU)represents a downward spinning reserve contribution of the non-CHPthermal unit i during the period t, SRU_(t) represents an upwardspinning reserve demand of the EPS during the period t and SRD_(t)represents a downward spinning reserve demand of the EPS during theperiod t.
 12. The method according to claim 7, wherein the constraintsbetween the supply/return water temperature differences of the nodes andthe heat outputs are denoted by a formula of${{{\sum\limits_{i \in I_{{CHS},k}^{CHP}}q_{i,t}^{CHP}} + {\sum\limits_{i \in I_{{CHS},k}^{HB}}q_{i,t}^{HB}}} = {C \cdot M_{k}^{N} \cdot \left( {\tau_{k,t}^{S} - \tau_{k,t}^{R}} \right)}},{{\text{∀}k} \in I_{HS}^{CHS}},{{\text{∀}t} \in T}$where, I_(CHS,k) ^(CHP) represents an index set of CHP units connectedto node k of the CHS, I_(CHS,k) ^(HB) represents an index set of heatingboilers connected to the node k of the CHS, q_(i,t) ^(CHP) represents aheat output of the CHP unit i during the period t, q_(i,t) ^(HB)represents a heat output of the heating boiler i during the period t, Crepresents a specific heat capacity of water, M_(k) ^(N) represents atotal mass flow rate of water at the node k of the CHS, τ_(k,t) ^(S)represents a water temperature of the node k in supply pipelines of theCHS during the period t, τ_(k,t) ^(R) represents a water temperature ofthe node k in return pipelines of the CHS during the period t, andI_(HS) ^(CHS) represents an index set of nodes with heat sourcesconnected in the CHS; the heat output constraints of the heating boilersare denoted by a formula of0≤q _(i,t) ^(HB) ≤Q _(i) ^(HB) ,∀iϵI ^(HB) ,∀tϵT where, Q _(i) ^(HB)represents an upper heat output bound of the heating boiler i; and thesupply water temperature constraints at the nodes with heat sourcesconnected are denoted by a formula ofT _(k) ^(S) ≤τ_(k,t) ^(S)≤ T _(k) ^(S) ,∀kϵI _(HS) ^(CHS) ,∀tϵT where,T_(k) ^(S) represents an upper bound of the water temperature at thenode k in the supply pipelines of the CHS and T_(k) ^(S) represents alower bound of the water temperature at the node k in the supplypipelines of the CHS.
 13. The method according to claim 7, wherein theconstraints between the supply/return water temperature differences ofthe nodes and the heat exchanges of the heat exchange stations in theCHS are denoted by a formula of${{\sum\limits_{n \in I_{{CHS},k}^{HES}}Q_{n,t}^{HES}} = {C \cdot M_{k}^{N} \cdot \left( {\tau_{k,t}^{S} - \tau_{k,t}^{R}} \right)}},{{\text{∀}k} \in I_{HES}^{CHS}},{{\text{∀}t} \in T}$where, I_(CHS,k) ^(HES) represents an index set of heat exchangestations connected to node k of the CHS, Q_(n,t) ^(HES) represents aheat exchange of heat exchange station n during the period t, Crepresents a specific heat capacity of water, M_(k) ^(N) represents atotal mass flow rate of water at the node k of the CHS, τ_(k,t) ^(S)represents a water temperature of the node k in supply pipelines of theCHS during the period t, τ_(k,t) ^(R) represents a water temperature ofthe node k in return pipelines of the CHS during the period t, andI_(HES) ^(CHS) represents an index set of nodes with heat exchangestations connected in the CHS; and the return water temperatureconstraints of the heat exchange stations are denoted by a formula ofT _(k) ^(R) ≤τ_(k,t) ^(R)≤ T _(k) ^(R) ,∀kϵI _(HES) ^(CHS) ,∀tϵT where,T_(k) ^(R) represents an upper bound of the water temperature at thenode k in the return pipelines of the CHS and T_(k) ^(R) represents alower bound of the water temperature at the node k in the returnpipelines of the CHS.
 14. The method according to claim 7, wherein theoperation constraints of the heating networks of the CHS are denoted bya formula of${{\sum\limits_{{k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},S}}\left( {M_{{k\; 2}\rightarrow{k\; 1}}^{B,S}{{HL}_{{k\; 2}\rightarrow{k\; 1}}^{S}\left( {\tau_{{{k\; 2}\rightarrow{k\; 1}},t}^{S,{temp}} - T_{t}^{AMB}} \right)}} \right)} = {\left( {\sum\limits_{{k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},S}}M_{{k\; 2}\rightarrow{k\; 1}}^{B,S}} \right)\left( {\tau_{{k\; 1},t}^{S} - T_{t}^{AMB}} \right)}},{{\text{∀}k\; 1} \in I^{CHS}},{{\text{∀}t} \in T}$${{\sum\limits_{{k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},R}}\left( {M_{{k\; 2}\rightarrow{k\; 1}}^{B,R}{{HL}_{{k\; 2}\rightarrow{k\; 1}}^{R}\left( {\tau_{{{k\; 2}\rightarrow{k\; 1}},t}^{R,{temp}} - T_{t}^{AMB}} \right)}} \right)} = {\left( {\sum\limits_{{k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},R}}M_{{k\; 2}\rightarrow{k\; 1}}^{B,R}} \right)\left( {\tau_{{k\; 1},t}^{R} - T_{t}^{AMB}} \right)}},{{\text{∀}k\; 1} \in I^{CHS}},{{\text{∀}t} \in T}$where, M_(k2→k1) ^(B,S) represents a mass flow rate of water transferredfrom node k2 to node k1 in supply pipelines of the CHS, M_(k2→k1) ^(B,R)represents a mass flow rate of return water transferred from the node k2to the node k1 in return pipelines of the CHS, I_(CHS,k1) ^(CN,S)represents an index set of child nodes of the node k1 in supplypipelines of the CHS, I_(CHS,k1) ^(CN,R) represents an index set ofchild nodes of the node k1 in return pipelines of the CHS, T_(t) ^(AMB)represents an ambient temperature during the period t, HL_(k2→k1) ^(S)represents a heat transfer factor of water transferred from the node k2to the node k1 in supply pipelines of the CHS, HL_(k2→k1) ^(R)represents a heat transfer factor of water transferred from the node k2to the node k1 in return pipelines of the CHS, wherein HL_(k2→k1) ^(S)and HL_(k2→k1) ^(R) are calculated by a formula of${{HL}_{{k\; 2}\rightarrow{k\; 1}}^{S} = {\exp\left( {- \frac{Y_{{k\; 2}\rightarrow{k\; 1}}^{S}L_{{k\; 2}\rightarrow{k\; 1}}^{S}}{{CM}_{{k\; 2}\rightarrow{k\; 1}}^{B,S}}} \right)}},{{\text{∀}k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},S}},{{\text{∀}k\; 1} \in I^{CHS}}$${{HL}_{{k\; 2}\rightarrow{k\; 1}}^{R} = {\exp\left( {- \frac{Y_{{k\; 2}\rightarrow{k\; 1}}^{R}L_{{k\; 2}\rightarrow{k\; 1}}^{R}}{{CM}_{{k\; 2}\rightarrow{k\; 1}}^{B,R}}} \right)}},{{\text{∀}k\; 2} \in I_{{CHS},{k\; 1}}^{{CN},R}},{{\text{∀}k\; 1} \in I^{CHS}}$where, Y_(k2→k1) ^(S) represents a heat transfer coefficient per unitlength of pipeline from the node k2 to the node k1 in the supplypipelines of the CHS, Y_(k2→k1) ^(R) represents a heat transfercoefficient per unit length of pipeline from the node k2 to the node k1in the return pipelines of the CHS, L_(k2→k1) ^(S) represents a lengthof the supply pipeline from the node k2 to the node k1, L_(k2→k1) ^(R)represents a length of the return pipeline from the node k2 to the nodek1; τ_(k2→k1,t) ^(S,temp) and τ_(k2→k1,t) ^(R,temp) are intermediatevariables representing temperature of the node k1 and only considering atransfer delay of water from its child node k2, wherein τ_(k2→k1,t)^(S,temp) and τ_(k2→k1,t) ^(R,temp) are denoted by a formula ofτ_(k2→k1,t) ^(S,temp)=(└Φ_(k2→k1) ^(S)┘+1−Φ_(k2→k1) ^(S))τ_(k2,t−└Φ)_(k2→k1) _(S) _(┘) ^(S)+(Φ_(k2→k1) ^(S)−└Φ_(k2→k1) ^(S)┘)τ_(k2,t−└Φ)_(k2→k1) _(S) _(┘−1) ^(S) ,∀k2ϵI _(CHS,k1) ^(CN,S) ,∀k1ϵI ^(CHS) ,∀tϵTτ_(k2→k1,t) ^(R,temp)=(└Φ_(k2→k1) ^(R)┘+1−Φ_(k2→k1) ^(R))τ_(k2,t−└Φ)_(k2→k1) _(R) _(┘) ^(R)+(Φ_(k2→k1) ^(R)−└Φ_(k2→k1) ^(R)┘)τ_(k2,t−└Φ)_(k2→k1) _(R) _(┘−1) ^(R) ,∀k2ϵI _(CHS,k1) ^(CN,R) ,∀k1ϵI ^(CHS) ,∀tϵTwhere, Φ_(k2→k1) ^(S) represents transfer time periods of water from thenode k2 to the node k1 in supply pipelines of the CHS, Φ_(k2→k1) ^(R)represents transfer time periods of water from the node k2 to the nodek1 in return pipelines of the CHS, and └⋅┘ represents a rounding downoperator.
 15. The method according to claim 7, wherein the CHPD model issummarized as a following quadratic programming QP problem by a formulaof:${\min\limits_{x_{E},x_{H}}{C_{E}\left( x_{E} \right)}} + {C_{H}\left( x_{H} \right)}$s.t.  A_(E)x_(E) ≤ b_(E) A_(H)x_(H) ≤ b_(H) Dx_(E) + Ex_(H) ≤ fwhere, x_(E) represents variables of the EPS, and the variables of theEPS comprises p_(i,t) ^(TU), ru_(i,t) ^(TU), rd_(i,t) ^(TU), p_(i,t)^(WD), p_(i,t) ^(CHP), q_(i,t) ^(CHP) and α_(i,t) ^(γ), in which p_(i,t)^(TU) represents a power output of the non-CHP thermal unit i during theperiod t, ru_(i,t) ^(TU) represents an upward spinning reservecontribution of the non-CHP thermal unit i during the period t, rd_(i,t)^(TU) represents a downward spinning reserve contribution of the non-CHPthermal unit i during the period t, p_(i,t) ^(WD) represents a poweroutput of the wind farm i during the period t, p_(i,t) ^(CHP) representsa power output of the CHP unit i during the period t, q_(i,t) ^(CHP)represents a heat output of the CHP unit i during the period t andα_(i,t) ^(γ) represents a coefficient of extreme point γ of the CHP uniti during the period t; x_(H) represents variables of the CHS, and thevariables of the CHS comprises q_(i,t) ^(HB), τ_(k,t) ^(S) and τ_(k,t)^(R), in which q_(i,t) ^(HB) represents a heat output of the heatingboiler i during the period t, τ_(k,t) ^(S) represents a watertemperature of the node k in supply pipelines of the CHS during theperiod t, and τ_(k,t) ^(R) represents a water temperature of the node kin return pipelines of the CHS during the period t; A_(E)x_(E)≤b_(E)refers to the constraints of the EPS; A_(H)x_(H)≤b_(H) refers to theconstraints of the CHS except the constraints between the supply/returnwater temperature differences of the nodes and the heat outputs; andDx_(E)+Ex_(H)≤f refers to the constraints between the supply/returnwater temperature differences of the nodes and the heat outputs.
 16. Themethod according to claim 15, wherein solving the CHPD model based onBenders decomposition to obtain dispatch parameters for the EPS and theCHS comprises: splitting the QP problem into an EPS problem and a CHSproblem; initializing an iteration number m as 0, the number of optimalcuts p as 0, and the number of feasible cuts q as 0; solving the EPSproblem to obtain a solution as x_(E) ^((m)) by a formula of$\min\limits_{x_{E}}{C_{E}\left( x_{E} \right)}$s.t.  A_(E)x_(E) ≤ b_(E); solving the CHS problem according to thesolution x_(E) ^((m)) by a formula of$\min\limits_{x_{E},x_{H}}{C_{H}\left( x_{H} \right)}$s.t.  A_(H)x_(H) ≤ b_(H) Dx_(E) + Ex_(H) ≤ f x_(E) = x_(E)^((m)) ifthe CHS problem is feasible, increasing p by 1 and generating an optimalcut ofA _(p) ^(OC) x _(E) +b _(p) ^(OC); if the CHS problem is infeasible,increasing q by 1 and generating an feasible cut ofA _(q) ^(FC) x _(E) ≤b _(q) ^(FC); solving the EPS problem by a formulaof${\min\limits_{x_{E}}{C_{E}\left( x_{E} \right)}} + C_{H\leftarrow E}$s.t.  A_(E)x_(E) ≤ b_(E) C_(H ← E) ≥ 0C_(H ← E) ≥ A_(i)^(OC)x_(E) + b_(i)^(OC), i = 1, 2, …  , pA_(i)^(FC)x_(E) ≤ b_(i)^(FC), i = 1, 2, …  , q; increasing theiteration number m by 1 and denoting a solution as x_(E) ^((m)); if∥x_(E) ^((m))−x_(E) ^((m−1))∥_(∞)<Δ, terminating the iteration to obtainthe dispatch parameters for the EPS and the CHS according to thesolution; and if ∥x_(E) ^((m))−x_(E) ^((m-1))∥^(∞)≥Δ, returning to actof solving the CHS problem according to the solution x_(E) ^((m)). 17.The method according to claim 16, wherein A^(OC)=λ^(T),b^(OC)=C_(H←E)(x_(E) ^((m)))−λ^(T)x_(E) ^((m)), and λ represents aLagrange multiplier of a constraint x_(E)=x_(E) ^((m)), andC_(H←E)(x_(E) ^((m))) represents an objective value of the CHS problem;A_(q) ^(FC) and b_(q) ^(FC) are calculated according to following acts:denoting a feasibility problem of the CHS problem as a formula of:$\max\limits_{x_{H}}{0^{T}x_{H}}$ s.t.  A_(H)x_(H) ≤ b_(H)Dx_(E)^((m)) + Ex_(H) ≤ f; introducing a relaxation term s to relax thefeasibility problem of the CHS problem as a formula of:$\max\limits_{x_{H},ɛ}{1^{T}ɛ}$ s.t.  A_(H)x_(H) ≤ b_(H)Dx_(E)^((m)) + Ex_(H) + 1^(T)ɛ ≤ f ɛ ≤ 0; denoting a Lagrangemultiplier of a constraint A_(H)x_(H)≤b_(H) in the relaxed feasibilityproblem of the CHS problem as û and a Lagrange multiplier of aconstraint Dx_(E) ^((m))+Ex_(H)+1^(T)ε≤f in the relaxed feasibilityproblem of the CHS problem as {circumflex over (v)}; and calculatingA_(g) ^(FC) and b_(q) ^(FC) according to a formula of:A _(q) ^(FC) ={circumflex over (v)} ^(T) D,b _(q) ^(FC) =û ^(T) b _(H)+{circumflex over (v)} ^(T) f.
 18. A dispatch apparatus for controllinga combined heat and power CHP system, wherein, the CHP system comprisesCHP units, non-CHP thermal units, wind farms and heating boilers; theCHP units, the non-CHP thermal units and the wind farms form an electricpower system EPS of the CHP system; the CHP units and the heatingboilers form a central heating system CHS of the CHP system; the EPS andthe CHS are isolable; and the device comprises: a processor; and amemory for storing instructions executable by the processor, wherein theprocessor is configured to: establish a combined heat and power dispatchCHPD model of the CHP system, wherein an objective function of the CHPDmodel is a minimizing function of a total generation cost of the CHPunits, the non-CHP thermal units, the wind farms and the heating boilersand constraints of the CHPD model are established based on generationcost of the CHP units, the non-CHP thermal units, the wind farms and theheating boilers; solve the CHPD model based on Benders decomposition toobtain dispatch parameters for the EPS and the CHS; and control the EPSand the CHS according to the corresponding dispatch parametersrespectively.
 19. A non-transitory computer-readable storage mediumhaving stored therein instructions that, when executed by a processor ofa computer, causes the computer to perform a dispatch method for acombined heat and power CHP system, wherein the CHP system comprises CHPunits, non-CHP thermal units, wind farms and heating boilers; the CHPunits, the non-CHP thermal units and the wind farms form an electricpower system EPS of the CHP system; the CHP units and the heatingboilers form a central heating system CHS of the CHP system; the EPS andthe CHS are isolable; and the method comprises: establishing a combinedheat and power dispatch CHPD model of the CHP system, wherein anobjective function of the CHPD model is a minimizing function of a totalgeneration cost of the CHP units, the non-CHP thermal units, the windfarms and the heating boilers and constraints of the CHPD model areestablished based on generation cost of the CHP units, the non-CHPthermal units, the wind farms and the heating boilers; solving the CHPDmodel based on Benders decomposition to obtain dispatch parameters forthe EPS and the CHS; and controlling the EPS and the CHS according tothe corresponding dispatch parameters respectively.